Perioperative allergic reactions manifest in various ways. The majority of systemic reactions occur during anesthesia within minutes of intravenous induction; however, agents which are administered via other routes may cause reactions after more than 15 minutes. Anaphylaxis during anesthesia may present in many different ways and the signs and symptoms, which do not vary from those of anaphylactic reactions in general, may be masked by hypovolemia, light, deep anesthesia or extensive regional blockade. Recommendations for treatment are based on available evidence in the literature. A treatment algorithm is suggested, with emphasis on the incremental titration of adrenaline and fluid therapy as first-line treatment. Increased focus on this subject will hopefully lead to prompt diagnosis and rapid, correct treatment.